'use client'

import React, { useState, useEffect, useCallback, useMemo, useRef } from 'react'
import { useSDK } from '@/lib/sdk'
import { StepHeader, STEP_EXPLANATIONS } from '@/components/sdk/StepHeader/StepHeader'
import {
  ScopeOverviewTab,
  ScopeWizardTab,
  ScopeDecisionTab,
  ScopeExportTab
} from '@/components/sdk/compliance-scope'
import type {
  ComplianceScopeState,
  ScopeProfilingAnswer,
  ScopeDecision,
  ApplicableRegulation,
  SupervisoryAuthorityInfo
} from '@/lib/sdk/compliance-scope-types'
import {
  createEmptyScopeState,
  STORAGE_KEY
} from '@/lib/sdk/compliance-scope-types'
import { complianceScopeEngine } from '@/lib/sdk/compliance-scope-engine'
import { getAllQuestions } from '@/lib/sdk/compliance-scope-profiling'
import { buildAssessmentPayload } from '@/lib/sdk/scope-to-facts'
import { resolveAuthorities } from '@/lib/sdk/supervisory-authority-resolver'

type TabId = 'overview' | 'wizard' | 'decision' | 'export'

const TABS: { id: TabId; label: string; icon: string }[] = [
  { id: 'overview', label: 'Uebersicht', icon: '📊' },
  { id: 'wizard', label: 'Scope-Profiling', icon: '📋' },
  { id: 'decision', label: 'Scope-Entscheidung', icon: '⚖️' },
  { id: 'export', label: 'Export', icon: '📤' },
]

export default function ComplianceScopePage() {
  const { state: sdkState, dispatch } = useSDK()

  // Project-specific storage key
  const projectStorageKey = sdkState.projectId
    ? `${STORAGE_KEY}_${sdkState.projectId}`
    : STORAGE_KEY

  // Active tab state
  const [activeTab, setActiveTab] = useState<TabId>('overview')

  // Migrate old decision format: drop decision if it has old-format fields
  const migrateState = (state: ComplianceScopeState): ComplianceScopeState => {
    if (state.decision) {
      const d = state.decision as Record<string, unknown>
      // Old format had 'level' instead of 'determinedLevel', or docs with 'isMandatory'
      if (d.level || !d.determinedLevel) {
        return { ...state, decision: null }
      }
    }
    return state
  }

  // Local scope state
  const [scopeState, setScopeState] = useState<ComplianceScopeState>(() => {
    // Try to load from SDK context first
    if (sdkState.complianceScope) {
      return migrateState(sdkState.complianceScope)
    }
    return createEmptyScopeState()
  })

  // Loading state
  const [isLoading, setIsLoading] = useState(true)
  const [isEvaluating, setIsEvaluating] = useState(false)

  // Guard against save-loop: tracks whether we're syncing FROM SDK → local state
  const syncingFromSdk = useRef(false)

  // Regulation assessment state
  const [applicableRegulations, setApplicableRegulations] = useState<ApplicableRegulation[]>([])
  const [supervisoryAuthorities, setSupervisoryAuthorities] = useState<SupervisoryAuthorityInfo[]>([])
  const [regulationAssessmentLoading, setRegulationAssessmentLoading] = useState(false)

  // Sync from SDK context when it becomes available (handles async loading).
  // The SDK context loads state from server/localStorage asynchronously, so
  // sdkState.complianceScope may arrive AFTER this page has already mounted.
  useEffect(() => {
    const ctxScope = sdkState.complianceScope
    if (ctxScope && ctxScope.answers?.length > 0) {
      syncingFromSdk.current = true
      setScopeState(migrateState(ctxScope))
      setIsLoading(false)
    } else if (isLoading) {
      // SDK has no scope data — try localStorage fallback, then give up
      try {
        const stored = localStorage.getItem(projectStorageKey)
        if (stored) {
          const parsed = migrateState(JSON.parse(stored) as ComplianceScopeState)
          if (parsed.answers?.length > 0) {
            setScopeState(parsed)
            dispatch({ type: 'SET_COMPLIANCE_SCOPE', payload: parsed })
          }
        }
      } catch (error) {
        console.error('Failed to load compliance scope from localStorage:', error)
      }
      setIsLoading(false)
    }
  // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [sdkState.complianceScope])

  // Fetch regulation assessment if decision exists on mount
  useEffect(() => {
    if (!isLoading && scopeState.decision && applicableRegulations.length === 0 && sdkState.companyProfile) {
      fetchRegulationAssessment(scopeState.decision)
    }
  // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [isLoading])

  // Save to localStorage and SDK context whenever LOCAL state changes (user edits).
  // Guarded: don't save empty state, and don't echo back what we just loaded from SDK.
  useEffect(() => {
    if (!isLoading && scopeState.answers.length > 0) {
      if (syncingFromSdk.current) {
        syncingFromSdk.current = false
        return
      }
      try {
        localStorage.setItem(projectStorageKey, JSON.stringify(scopeState))
        dispatch({ type: 'SET_COMPLIANCE_SCOPE', payload: scopeState })
      } catch (error) {
        console.error('Failed to save compliance scope state:', error)
      }
    }
  }, [scopeState, isLoading, dispatch])

  // Handle answers change from wizard
  const handleAnswersChange = useCallback((answers: ScopeProfilingAnswer[]) => {
    setScopeState(prev => ({
      ...prev,
      answers,
      lastModified: new Date().toISOString(),
    }))
  }, [])

  // Fetch regulation assessment from Go AI SDK
  const fetchRegulationAssessment = useCallback(async (decision: ScopeDecision) => {
    const profile = sdkState.companyProfile
    if (!profile) return

    setRegulationAssessmentLoading(true)
    try {
      const payload = buildAssessmentPayload(profile, scopeState.answers, decision)
      const res = await fetch('/api/sdk/v1/ucca/obligations/assess-from-scope', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify(payload),
      })
      if (!res.ok) throw new Error(`HTTP ${res.status}`)
      const data = await res.json()

      // Set applicable regulations from response
      const regs: ApplicableRegulation[] = data.overview?.applicable_regulations || data.applicable_regulations || []
      setApplicableRegulations(regs)

      // Derive supervisory authorities
      const regIds = regs.map(r => r.id)
      const authorities = resolveAuthorities(
        profile.headquartersState,
        profile.headquartersCountry || 'DE',
        regIds
      )
      setSupervisoryAuthorities(authorities)
    } catch (error) {
      console.error('Failed to fetch regulation assessment:', error)
    } finally {
      setRegulationAssessmentLoading(false)
    }
  }, [sdkState.companyProfile, scopeState.answers])

  // Handle evaluate button click
  const handleEvaluate = useCallback(async () => {
    setIsEvaluating(true)
    try {
      // Run the compliance scope engine
      const decision = complianceScopeEngine.evaluate(scopeState.answers)

      // Update state with decision
      setScopeState(prev => ({
        ...prev,
        decision,
        lastModified: new Date().toISOString(),
      }))

      // Switch to decision tab to show results
      setActiveTab('decision')

      // Fetch regulation assessment in the background
      fetchRegulationAssessment(decision)
    } catch (error) {
      console.error('Failed to evaluate compliance scope:', error)
    } finally {
      setIsEvaluating(false)
    }
  }, [scopeState.answers, fetchRegulationAssessment])

  // Handle start profiling from overview
  const handleStartProfiling = useCallback(() => {
    setActiveTab('wizard')
  }, [])

  // Handle reset
  const handleReset = useCallback(() => {
    const emptyState = createEmptyScopeState()
    setScopeState(emptyState)
    setActiveTab('overview')
    localStorage.removeItem(projectStorageKey)
  }, [])

  // Calculate completion statistics
  const completionStats = useMemo(() => {
    const allQuestions = getAllQuestions()
    const requiredQuestions = allQuestions.filter(q => q.required)
    const totalQuestions = requiredQuestions.length
    const answeredIds = new Set(scopeState.answers.map(a => a.questionId))
    const answeredQuestions = requiredQuestions.filter(q => answeredIds.has(q.id)).length

    const completionPercentage = totalQuestions > 0
      ? Math.round((answeredQuestions / totalQuestions) * 100)
      : 0

    const isComplete = answeredQuestions === totalQuestions

    return {
      total: totalQuestions,
      answered: answeredQuestions,
      percentage: completionPercentage,
      isComplete,
    }
  }, [scopeState.answers])

  // Auto-enable evaluation when all questions are answered
  const canEvaluate = useMemo(() => {
    return completionStats.isComplete
  }, [completionStats.isComplete])

  // Mark sidebar step as complete when all required questions answered AND decision exists
  useEffect(() => {
    if (completionStats.isComplete && scopeState.decision) {
      dispatch({ type: 'COMPLETE_STEP', payload: 'compliance-scope' })
    }
  }, [completionStats.isComplete, scopeState.decision, dispatch])

  if (isLoading) {
    return (
      <div className="max-w-6xl mx-auto p-6">
        <div className="flex items-center justify-center h-64">
          <div className="text-gray-500">Loading...</div>
        </div>
      </div>
    )
  }

  return (
    <div className="max-w-6xl mx-auto space-y-6 p-6">
      {/* Step Header */}
      <StepHeader
        stepId="compliance-scope"
        title="Compliance Scope Engine"
        description="Umfang und Tiefe Ihrer Compliance-Dokumentation bestimmen"
        explanation="Die Scope Engine analysiert Ihr Unternehmen anhand von 35 Fragen in 6 Bereichen und bestimmt deterministisch, welche Dokumente in welcher Tiefe benoetigt werden. Das 4-Level-Modell reicht von L1 (Lean Startup) bis L4 (Zertifizierungsbereit). Hard Triggers wie Art. 9 Daten oder Minderjährige heben das Level automatisch an."
        tips={[
          {
            icon: 'lightbulb',
            title: 'Deterministisch',
            description: 'Alle Entscheidungen sind nachvollziehbar — keine KI, keine Black Box. Jede Empfehlung hat eine auditfähige Begründung.'
          },
          {
            icon: 'info',
            title: '4-Level-Modell',
            description: 'L1 (Lean Startup) bis L4 (Zertifizierungsbereit). Das Level bestimmt Dokumentationstiefe und -umfang.'
          },
          {
            icon: 'warning',
            title: 'Hard Triggers',
            description: 'Besondere Datenkategorien (Art. 9), Minderjährige oder Zertifizierungsziele heben das Level automatisch an.'
          },
        ]}
      />

      {/* Progress Indicator */}
      {completionStats.answered > 0 && (
        <div className="bg-purple-50 border border-purple-200 rounded-lg p-4">
          <div className="flex items-center justify-between mb-2">
            <div className="text-sm font-medium text-purple-900">
              Fortschritt: {completionStats.answered} von {completionStats.total} Fragen beantwortet
            </div>
            <div className="text-sm font-semibold text-purple-700">
              {completionStats.percentage}%
            </div>
          </div>
          <div className="w-full bg-purple-200 rounded-full h-2">
            <div
              className="bg-purple-600 h-2 rounded-full transition-all duration-300"
              style={{ width: `${completionStats.percentage}%` }}
            />
          </div>
        </div>
      )}

      {/* Main Content Card */}
      <div className="bg-white rounded-xl border border-gray-200 shadow-sm">
        {/* Tab Navigation */}
        <div className="border-b border-gray-200 px-6">
          <nav className="flex gap-6 -mb-px">
            {TABS.map(tab => (
              <button
                key={tab.id}
                onClick={() => setActiveTab(tab.id)}
                className={`
                  flex items-center gap-2 py-4 px-1 border-b-2 font-medium text-sm transition-colors
                  ${activeTab === tab.id
                    ? 'border-purple-600 text-purple-700'
                    : 'border-transparent text-gray-600 hover:text-gray-800 hover:border-gray-300'
                  }
                `}
              >
                <span className="text-lg">{tab.icon}</span>
                <span>{tab.label}</span>
                {tab.id === 'wizard' && completionStats.answered > 0 && (
                  <span className="ml-1 px-2 py-0.5 text-xs rounded-full bg-purple-100 text-purple-700">
                    {completionStats.percentage}%
                  </span>
                )}
                {tab.id === 'decision' && scopeState.decision && (
                  <span className="ml-1 w-2 h-2 rounded-full bg-green-500" />
                )}
              </button>
            ))}
          </nav>
        </div>

        {/* Tab Content — pb-28 verhindert dass sticky Footer die unteren Buttons verdeckt */}
        <div className="p-6 pb-28">
          {activeTab === 'overview' && (
            <ScopeOverviewTab
              scopeState={scopeState}
              completionStats={completionStats}
              onStartProfiling={handleStartProfiling}
              onReset={handleReset}
              onGoToWizard={() => setActiveTab('wizard')}
              onGoToDecision={() => setActiveTab('decision')}
              onGoToExport={() => setActiveTab('export')}
            />
          )}

          {activeTab === 'wizard' && (
            <ScopeWizardTab
              answers={scopeState.answers}
              onAnswersChange={handleAnswersChange}
              onEvaluate={handleEvaluate}
              canEvaluate={canEvaluate}
              isEvaluating={isEvaluating}
              completionStats={completionStats}
            />
          )}

          {activeTab === 'decision' && (
            <ScopeDecisionTab
              decision={scopeState.decision}
              answers={scopeState.answers}
              onBackToWizard={() => setActiveTab('wizard')}
              onGoToExport={() => setActiveTab('export')}
              canEvaluate={canEvaluate}
              onEvaluate={handleEvaluate}
              isEvaluating={isEvaluating}
              applicableRegulations={applicableRegulations}
              supervisoryAuthorities={supervisoryAuthorities}
              regulationAssessmentLoading={regulationAssessmentLoading}
              onGoToObligations={() => { window.location.href = '/sdk/obligations' }}
            />
          )}

          {activeTab === 'export' && (
            <ScopeExportTab
              scopeState={scopeState}
              onBackToDecision={() => setActiveTab('decision')}
            />
          )}
        </div>
      </div>

      {/* Quick Action Buttons (Fixed at bottom on mobile) */}
      <div className="sticky bottom-6 flex justify-between items-center gap-4 bg-white rounded-lg border border-gray-200 p-4 shadow-lg">
        <div className="flex items-center gap-3">
          <div className="text-sm text-gray-600">
            {completionStats.isComplete ? (
              <span className="flex items-center gap-2 text-green-700">
                <span className="text-lg">✓</span>
                <span className="font-medium">Profiling abgeschlossen</span>
              </span>
            ) : (
              <span className="flex items-center gap-2">
                <span className="text-lg">📋</span>
                <span>
                  {completionStats.answered === 0
                    ? 'Starten Sie mit dem Profiling'
                    : `Noch ${completionStats.total - completionStats.answered} Fragen offen`
                  }
                </span>
              </span>
            )}
          </div>
        </div>

        <div className="flex items-center gap-3">
          {activeTab !== 'wizard' && completionStats.answered > 0 && (
            <button
              onClick={() => setActiveTab('wizard')}
              className="px-4 py-2 text-sm font-medium text-purple-700 bg-purple-50 hover:bg-purple-100 rounded-lg transition-colors"
            >
              Zum Fragebogen
            </button>
          )}

          {canEvaluate && activeTab !== 'decision' && (
            <button
              onClick={handleEvaluate}
              disabled={isEvaluating}
              className="px-4 py-2 text-sm font-medium text-white bg-purple-600 hover:bg-purple-700 rounded-lg transition-colors disabled:opacity-50 disabled:cursor-not-allowed"
            >
              {isEvaluating ? 'Evaluiere...' : 'Scope evaluieren'}
            </button>
          )}

          {scopeState.decision && activeTab !== 'export' && (
            <button
              onClick={() => setActiveTab('export')}
              className="px-4 py-2 text-sm font-medium text-white bg-green-600 hover:bg-green-700 rounded-lg transition-colors"
            >
              Exportieren
            </button>
          )}
        </div>
      </div>

      {/* Debug Info (only in development) */}
      {process.env.NODE_ENV === 'development' && (
        <details className="bg-gray-50 border border-gray-200 rounded-lg p-4">
          <summary className="cursor-pointer text-sm font-medium text-gray-700">
            Debug Information
          </summary>
          <div className="mt-3 space-y-2 text-xs font-mono">
            <div>
              <span className="font-semibold">Active Tab:</span> {activeTab}
            </div>
            <div>
              <span className="font-semibold">Total Answers:</span> {scopeState.answers.length}
            </div>
            <div>
              <span className="font-semibold">Answered:</span> {completionStats.answered} ({completionStats.percentage}%)
            </div>
            <div>
              <span className="font-semibold">Has Decision:</span> {scopeState.decision ? 'Yes' : 'No'}
            </div>
            {scopeState.decision && (
              <>
                <div>
                  <span className="font-semibold">Level:</span> {scopeState.decision.determinedLevel}
                </div>
                <div>
                  <span className="font-semibold">Score:</span> {scopeState.decision.scores?.composite_score}
                </div>
                <div>
                  <span className="font-semibold">Hard Triggers:</span> {scopeState.decision.triggeredHardTriggers.length}
                </div>
              </>
            )}
            <div>
              <span className="font-semibold">Last Modified:</span> {scopeState.lastModified || 'Never'}
            </div>
            <div>
              <span className="font-semibold">Can Evaluate:</span> {canEvaluate ? 'Yes' : 'No'}
            </div>
          </div>
        </details>
      )}
    </div>
  )
}